It could be anything on the front end and even as simple as tires. How many miles do you have on your tires? I worked with a guy that thought he had front end (tire rods/wheel bearings) problems and steering system problems like a rack n pinion/power steering pump. He had the rack n pinion tested at the dealer which turned out OK. He eventually replaced his tires and had a complete alignment done which corrected his problem. Just my 2 cents.
If you had brake work done, make sure the caliper mounting bracket and caliper is properly torqued down to specs. Also check wheel nut torque for 100 ft-lbs. Good luck!